1. Field of the Invention
The present invention relates to a radiation tolerant unit metal oxide semiconductor field effect transistor (MOSFET) and a method and apparatus for modeling a channel of a semiconductor device. More particularly, the present invention relates to a radiation tolerant dummy gate-assisted (DGA) unit MOSFET wherein the transistor layout of a unit MOSFET is modified so that the unit MOSFET is resistant to radiation, and to a method and apparatus for modeling a channel of a semiconductor device that can enhance semiconductor design efficiency by enabling rapid modeling of electrical characteristics of the channel region of a semiconductor device such as a DGA MOSFET when the channel geometry is varied according to design of the semiconductor device.
2. Description of the Related Art
When a unit MOSFET (metal oxide semiconductor field effect transistor) is exposed to radiation for a long time, leakage current is induced and turn-off operation of the MOSFET may be blocked. Hence, electronic components operated in radioactive environments (such as outer space, planetary exploration, and in nuclear reactors in nuclear power plants) must be resistant to radiation.
In typical circuit design, operating characteristics of a semiconductor circuit are determined by adjusting the width over length (W/L) ratio of a semiconductor device. For example, to design a circuit using a unit MOSFET having a given channel region geometry, it is necessary to develop a model with an effective W/L ratio suitable for the channel region geometry. However, an analytical solution for a desired channel region geometry may not exist. In this case, only numerical analysis using a computer may be utilized. Designing and computing a channel region model with a specific geometry on a three-dimensional simulator may require a lot of time and effort. Circuit design may need various types of semiconductor devices with different structures, and hence it may be practically infeasible to perform three-dimensional simulation for each unit semiconductor device for realistic circuit design.